Incorporation process for materials used to form photographic layers

ABSTRACT

THE EMULSIFICATION OF ADDITIVES INTO A PHOTOGRAPHIC EMULSION IS STABILIZED BY COMBINING THE ADDITIVE WITH CERTAIN SECONDARY CARBOXYLIC ACIDS BEFORE THEY ARE EMULSIFIED.

United States Patent US. CI. 96-84 11 Claims ABSTRACT OF THE DISCLOSUREThe emulsification of additives into a photographic emulsion isstabilized by combining the additive with certain secondary carboxylicacids before they are emulsified.

The present invention relates to a process for incorporating substancesin materials which are used to form photographic layers and auxiliarylayers.

It is already known that emulsifiable compounds such as colour couplers,UV absorbers, white toners and similar additives may be incorporated ingelatine solutions by using so-called oil forming agents. According toUS. Pats. Nos. 2,322,027 and 2,533,514, for example, colour couplers areincorporated in water-soluble colloidal materials commonly used in theproduction of photographic products by dissolving the colour coupler inan organic liquid of relatively high boiling point which is insoluble inwater, and emulsifying or dispersing the solution in the colloidalmaterial. This process has the disadvantage that hydrophilic developers,e.g. N-butyl-N-w-sulphobutylp-phenylenediamine, penetrate the oildroplets only to a slight extent, if at all. This causes loss insensitivity, flattening of the gradation and a reduced image density.Also, residues of hydrophobic developer may be retained in the dropletsand cause fogging when the photographic material is treated in oxidisingbleaching baths.

Hydrophilic substances such as colour couplers which carry a carboxylgroup are incorporated in gelatine in the form of their sodium salts.Since the gelatine solutions are subsequently adjusted to a pH of 6.2 to6.5, these compounds are generally present in microcrystallinedistribution. The protective colloidal action of gelatine is in manycases insufiicient, so that recrystallisation occurs influencingsensitivity, gradation and colour brilliance in an uncontrollablemanner.

Although hydrophilic substances such as colour couplers which carry SO Hgroups are generally more compatible with gelatine than the abovementioned compounds, recrystallisation still occurs in many cases duringdigestion of the gelatin, especially in the case of compounds that havean enolate form which promotes solubility in an alkaline medium. At thepH values of 6.2-6.5 to which most emulsions are adjusted, the action ofthe SO Na group in preventing recrystallisation is no longer sufiicient.This again leads to a loss in sensitivity, reduction in the colourbrilliance and loss in gradation. The use of lithium salts and increasedamounts of wetting agents has been found to also bring no significantimprovements.

Numerous hydrophilic substances of the above mentioned types, moreover,have the property of increasing the viscosity of the casting solution,in some cases to such an extent that such solutions can no longer beworked up.

It is an object of the present invention to provide an incorporationprocess which does not have the above mentioned disadvantages.

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We have now found a process for the production of photographic layerswhich contain additional substances emulsified therein in the form of asolution and the resulting emulsified mixture being applied to asupport, which process is characterised in that the additionalsubstances are emulsified together with compounds of the followinggeneral formula:

in which R represents an alkyl or alkylene group which has 1 to 18carbon atoms, preferably 5 to 12 carbon atoms and is branched and may besubstituted, preferably by OH and/or OR groups R represents a hydrogenatom, an alkyl or alkylene group which has 1 to 18 carbon atoms,preferably 5 to 12 carbon atoms and is branched and may be substituted,preferably by OH and/or OR groups, and Q represents an alkyl group whichhas 1 to 9 carbon atoms and may be substituted, preferably by COOH, orone of the groups COX or -CH COX in which X may have the followingmeaning: (1) a hydrogen atom, a hydroxy group, an alkoxy group with 1 to18 carbon atoms and preferably 5 to 12 carbon atoms, (2) anO-alkylene-[O-alkylene] -O-alkyl group in which the alkylene and alkylradical preferably contain 1 to 4 carbon atoms and n denotes 0 to 10,

(3) an amino group, especially a substituted amino group such as1H-alkyl,

alkyl aryl aryl N NH-ary1,-N N

alkyl aryl alkyl NH-cycloalkyl, or

in which the alkyl radical may contain up to 21 carbon atoms, ispreferably branched and may in turn be substituted as may also the arylradical, especially with such groups as OH, COOH, OCH CN and phenyl,

(4) a hydrazine group which may be substituted by an alkyl grouppreferably having 1 to 5 carbon atoms or by the group which alkylsubstituents may in particular be substituted by OH, COOH, OCH and CENgroups,

(5 a hydroxylamino group. (6) or a group -0-oH oH3)oH21 IY in which Yrepresents the group wherein R has the above indicated meaning and Zstands for CH or is equal to Y.

The following compounds are particularly suitable for use in the processof the invention;

The radical i-C H appearing in many compounds in the above listrepresents the group l,1,3,5-tetramethylocten-(2)-yl whose structuralformula is Versatic acid 911 is an isomeric mixture of highly branchedtertiary and secondary carboxylic acids having 9 to 11 carbon atoms, andVersatic acid 1519 is a mixture of carboxylic acids of the same typehaving 15 to 19 carbon atoms.

The method of preparation of the compounds used in the present inventionis generally known. In order to prepare the type of compound whichcontains a free carboxyl group in addition to the radical COX definedabove, monoalkylated cyclic carboxylic acid anhydrides are reacted withalcohols or with amines.

The process of the present invention is generally carried out asfollows:

Emulsifiable substances such as colour couplers, UV absorbents, whitetoners or stabilisers are dissolved together with the compoundsaccording to the present invention, in an organic solvent which isimmiscible with water and emulsified with the casting solution for thephotographic layer, using an emulsifying apparatus. The emulsifyingapparatuses used for this purpose may, for example, be high speedstirrers, so-called mixing sirens, ultraturrax or ultrasoundapparatuses.

Hydrophilic substances, e.g. the above mentioned colour couplers whichcontain carboxyl groups or hydrophilic substances such as colourcouplers which contain SO H groups are incorporated by a differentmethod. In this case, the compounds of the present invention aredissolved in an alkaline medium together with the additives which arepresent in an alkali soluble form and a wetting agent, and this solutionis added with intensitive stirring to an acidified casting solution asexplained above. The pH of the casting solution is thereby shifted to6.2-6.5. Certain colour couplers which do not contain SO H or COOHgroups and which are soluble in alkali as enolates can be incorporatedin the same manner.

The compounds of the present invention have the advantage that, apartfrom a very pronounced tendency to prevent crystallisation, especiallyin the presence of colour couplers which have been incorporated byemulsification, they do not prevent the coupling of oxidised colourdevelopers. The compounds form soaps at alkaline pH values, i.e. duringdevelopment. In contrast to lower carboxylic acids or those which haveonly a short fatty acid radical, the additives used with the compoundsaccording to the present invention do not separate out in an alkalinemedium. They therefore also prevent precipitation of the dye produced orthe appearance or turbulent colour surfaces. The separation of colourcomponents by crystallisation which might otherwise occur even duringdigestion is also prevented. Furthermore, in contrast to the knownhydrophobic oil-forming agents, the compounds used according to thepresent invention cause neither flattening of the gradation norreduction in the image density and in addition they substantiallyprevent the increase in viscosity which many colour couplers containingCOOH or SO H groups cause during digestion.

The compounds of the present invention are generally employed in theproportion of 0.1 to 10 parts by weight per part by weight of thesubstance which is to be incorporated, the preferred range lying between0.3 and 1 part by weight. The use of higher concentrations of up to 10parts by weight is of interest in cases in which only small quantitiesof an additive, e.g. a sta-biliser, are to be incorporated into thecasting solution.

Examples of suitable organic solvents which are immiscible with Waterare the chlorinated short-chained aliphatic compounds such as methylenedichloride, as well phatic compounds such as methylene di chloride, aswell as ethyl acetate.

The binder used for the photographic layers is preferably gelatine butthis may be partly replaced by other film-forming natural or syntheticpolymers. Suitable polymers for this purpose include alginic acid andits derivatives such as its salts, esters, or amides, carboxymethylcellulose, alkyl cellulose, starch and its derivatives, polyvinylalcohol, copolymers of vinyl alcohol and vinyl acetate, polyvinylpyrrolidone, anionic polyurethanes and other latices such as copolymersof acrylic ester, acrylonitrile and acrylamide.

The photographic layers may contain any known additives such as anti-fogagents, stabilisers, hardeners, plasticisers and wetting agents. Inaddition, they may be both chemically and spectrally sensitised.

The light sensitive emulsions may be chemically sensitised by carryingout the ripening in the presence of small quantities ofsulphur-containing compounds such as allyl isothiocyanate, allylthiourea and sodium thiosulphate. The light sensitive emulsions may alsobe sensitised with reducing agents, e.g. the tin compounds described inBelgian Pats. Nos. 493,464 and 568,687, and theiminoaminomethanesulphinic acid compounds described in Belgian Pat. No.547,323 or small quantities of noble metal compounds such as compoundsof gold, platinum, palladium, iridium, ruthenium and rhodium. Theemulsions may also be sensitised with polyalkylene oxide derivatives,e.g. a polyethylene oxide having a molecular weight of between 1000 and20,000, condensation products of alkylene oxide and aliphatic alcohols,glycols, cyclic dehydration products of hexitols, alkyl substitutedphenols, aliphatic carboxylic acids, aliphatic amines, aliphaticdiamines and amides. The condensation products have a molecular weightof at least 700, preferably more than 1000. To achieve special effects,combinations of these sensitisers may, of course, be used as describedin Belgian Pat. No. 537,278 and in British patent specification No.727,982.

EXAMPLE 1 A solution of 40 g. of the following blue green coupler HsC 511 and 20 g. of Compound 3 dissolved in 160 cc. of ethyl acetate isemulsified in 1 kg. of a 10% gelatine solution at 50 C. After removal ofthe solvent in a thin layer evaporator, the emulsion is added to 1 kg.of a red sensitised silver halide gelatine emulsion which contains 0.33mol of silver bromide, 0.0075 mol of silver iodide and g. of gelatineper kg.

The mixture prepared in this Way is used as a red sensitive layercontaining a blue green coupler, in a multilayered colour photographicmaterial in the usual manner.

The flattening of the gradation and the reduction in the colour densitywhich occur with the known hydrophilic developers do not occur in thiscase.

7 EXAMPLE 2 40 g. of the following blue green coupler or: @iD-b ONHC HuEXAMPLE 3 25 g. of the following purple coupler are emulsified in 1 kg.of 10% gelatine solution in the same manner as in Example 1 togetherwith 12.5 g. of Compound 26 and added to 1 kg. of a green sensitisedhalide gelatine emulsion.

The mixture is worked up as in Example 1. The green sensitive layer hasthe same properties as the emulsion described in Example 1.

EXAMPLE 4 36 g. of the following yellow coupler iuHaa Q-o 001120 ONH- FCOOH together with 18 g. of Compound 30 are dissolved in a mixture of360 ml. of water, 40 ml. of 5 N NaOH, and the resulting solution 75 ml.of methanol and emulsified at 40 C. in 1 litre of a gelatine solutionwhich contains 90 ml. of a 21% solution of monosodium citrate. Theemulsion thus formed has a pH of 6.1 and is added to 1 kg. of a bluesensitive silver halide gelatine emulsion which contains 0.33 mol ofsilver bromide, 0.0075 mol of silver iodide and 90 g. of gelatine perkg.

The final mixture is worked up in the same manner as in Example 1 togive a blue sensitive layer which contains yellow coupler and has thesame properties as the emulsion obtained in Example 1. When compound 30is omitted, the coupler crystallises out after a short time.

EXAMPLE 5 22.5 g. of the following purple coupler together with 12 g. ofCompound 28 and 1 g. of the his- (2-ethyl)-hexyl ester of sulphosuccinicacid as wetting agent are dissolved in a mixture of 230 ml. of water, 30m1. of 5 N NaOH and 75 ml. of methanol and thesolution emulsified at 40C. in 1 litre of a 10% gelatine solution which contains 40 ml. of a 21%monosodium citrate solution. The resulting emulsion is added to 1 kg. ofa green sensitised silver halide gelatine emulsion which contains 0.33mol of silver bromide, 0.0075 mol of silver iodide and g. of gelatineper kg.

When the mixture has been worked up in the manner described previously,similar results to those indicated in Example 4 are obtained.

EXAMPLE 6 25 g. of the following purple coupler l SOaH together with12.5 g. of Compound 4 and 1 g. of the bis- (2-ethyl)-hexyl ester ofsulphosuccinic acid as wetting agent are dissolved in a mixture of 250ml. of water, 50 ml. of 1 N lithium hydroxide solution and 75 ml. ofmethanol and the solution emulsified at 40 C. in 1 litre of a 10%gelatine solution which contains 40 ml. of 21% monosodium citratesolution.

The emulsion is added to 1 kg. of a green sensitised silver halidegelatine emulsion which contains 0.33 mol of silver bromide 0.0075 molof silver iodide and 90 g. of gelatine per kg. The mixture is worked upas before. When Compound 4 is omitted the coupler crystallises out ondigestion.

EXAMPLE 7 40 g. of the following yellow coupler SO NHCH:

together with 20 g. of Compound 3 and 1 g. of the his- (2-ethyl)-hexylester of sulphosuccinic acid as wetting agent are dissolved in a mixtureof 350 ml. of water, 20 ml. of 5 N NaOH and 75 ml. of methanol and thesolution stirred into 1 kg. of blue sensitive halide gelatine emulsionwhich contains 0.33 mol of silver bromide, 0.0075 mol of silver iodideand g. of gelatine per kg. 40 ml. of 21% monosodium citrate solution areadded to the emulsion before the solution of the components is stirredin.

The result is similar to that obtained in Example 6.

EXAMPLE 8 40 g. of the yellow coupler used in Example 7 together with 20g. of Compound 2 are dissolved as indicated in that example and added to1 kg. of a blue sensitive silver halide gelatine emulsion which contains0.33 mol of silver bromide, 0.0075 mol of silver iodide and 120 g. ofgelatine per kg. and to which 40 ml. of a 21% monosodium citratesolution have previously been added. The result is similar to thatobtained in Example 6.

EXAMPLE 9 40 g. of the yellow coupler used in Example 7 together with 20g. of Compound 7 are dissolved as described in that example and added to1 kg. of a blue sensitive silver halide gelatine emulsion which contains0.33 mol of silver bromide, 0.0075 mol of silver iodide and 120 g. ofgelatine per kg.-The result'is similar to that obtained in Example 6.

9 EXAMPLE 10 30 g. of the following UV absorber Ho (min N together with10 g. of Compound 25 are dissolved in ethyl acetate and emulsified in 1kg. of a gelatine solution. The emulsion is cast as a UV protectivelayer over a colour photographic material.

The protective layer produced by the process according to the inventionis clear whereas a layer produced without Compound 25 remains cloudy.

EXAMPLE 11 30 g. of the UV absorber used in Example 10 together with g.of Compound 28 are dissolved in ethyl acetate and emulsified in 1 kg. ofa 10% gelatine solution. The emulsion is cast as a UV protective layerover a colour photographic material. The result is similar to thatobtained in Example 10.

EXAMPLE 12 0.5 g. of the following white toner N- N O Cfis 100 mg. of astabiliser of the following formula together with 3 g. of Compound 3 aredissolved in 10 ml. of methylene di chloride and the solution emulsifiedin 1 kg. of a 10% gelatine solution. The emulsion is used as aprotective layer for colour photographic material.

The presence of Compound 3 prevents diffusion of the stabiliser into theadjacent layers.

EXAMPLE 14 22 g. of the following purple coupler together with 15 g. ofCompound 28 and 1 g. of the bis- (2-ethy1)-hexyl ester of sulphosuccinicacid as wetting agent are dissolved in a mixture of 400 ml. of water,ml. of 5 N NaOH and 60 ml. of methanol and the solution emulsified at 40C. in 1 litre of 10% gelatine solution which contains 40 ml. of a 21%monosodium citrate solution. The emulsion is added to 1 kg. of a greensensitised silver halide gelatine emulsion which contains 0.33 mol ofsilver bromide, 0.0075 mol of silver iodide and g. of gelatine per kg.The addition of Compound 28 prevents the steep rise in viscosity causedby the colour coupler when Compound 28 is absent.

We claim:

1. In the process of emulsifying materials into an aqueous dispersion ofa hydrophilic photographic binder, the improvement according to whichthe emulsification is effected with the help of at least one compoundhaving the formula:

where R represents an alkyl or unsaturated alkyl and has at least 5carbon atoms,

Q is COX or an alkyl having up to 9 carbon atoms and a COX substituent,and

X is hydroxy, alkoxy of up to 18 carbons which may be alkoxy or aminosubstituted, or amino substituted by alkyl or aryl radicals of up to 21carbons 'which radicals can be OH, CN, alkoxy, carboxy or aminesubstituted, or a hydrazine or hydroxylamine radical and an amounteffective to stabilize the emulsification.

2. In the process of emulsifying materials into a gelatin emulsion, theimprovement according to which the emulsification is effected with thehelp of at least one compound having the formula:

where R represents a branched alkyl or unsaturated alkyl and has from 5to 12 carbon atoms,

Q is COX or CH COX, and

X is hydroxy, alkoxy of up to 18 carbons which may be alkoxy or aminosubstituted, or amino substituted by alkyl or aryl radicals of up to 21carbons which radicals can be OH, CN, alkoxy, carboxy or aminesubstituted, or a hydrazine or hydroxylamine radical and in an amounteffective to stabilize the emulsification.

3. The combination of claim 2 in which R is l,l,3,5- tetramethyl-octen-(2 -yl.

4. The combination of claim 2 in which the material to be emulsified isfirst dissolved in a volatile organic solvent along with the stabilizingcompound, and the solution thus formed is emulsified into the gelatinemul- 5. The combination of claim 4 in which the solvent is methylenedichloride.

6. The combination of claim 4 in which the solvent is ethyl acetate.

7. The combination of claim 2 in which the material to be emulsified issoluble in aqueous alkali, it is dissolved in an aqueous alkalinesolution along with the stabilizing compound and the resulting solutionemulsified into the gelatin emulsion.

8. A photographic gelatin emulsion containing emulsified photographicadditive particles, said particles also having at least one compound ofthe formula:

t R-C-COOH where R represents an alkyl or unsaturated alkyl and has atleast 5 carbon atoms,

Q is COX or an alkyl having up to 9 carbon atoms and a COX substituent,and

X is hydroxy, alkoxy of up to 18 carbons which may be alkoxy or aminosubstituted, or amino substituted by alkyl or aryl radicals of up to 21carbons which radicals can be OH, CN, alkoxy, carboxy or aminesubstituted, or a hydrazine of hydroxylamine radical and in an amounteffective to stabilize the emulsification.

9. The combination of claim 8 in which the photographic additive is acolor coupler.

10. The combination of claim 8 in which the photographic additive is aUV absorber.

11. The combination of claim 8 in which the photographic additive is awhite toner.

References Cited UNITED STATES PATENTS J. TRAVIS BROWN, Primary ExaminerUS. Cl. X.R.

